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@@ -0,0 +1,186 @@
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+/*
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+ * kernel/cpu_acct.c - CPU accounting cgroup subsystem
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+ *
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+ * Copyright (C) Google Inc, 2006
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+ *
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+ * Developed by Paul Menage (menage@google.com) and Balbir Singh
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+ * (balbir@in.ibm.com)
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+ *
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+ */
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+
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+/*
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+ * Example cgroup subsystem for reporting total CPU usage of tasks in a
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+ * cgroup, along with percentage load over a time interval
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+ */
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+
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+#include <linux/module.h>
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+#include <linux/cgroup.h>
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+#include <linux/fs.h>
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+#include <linux/rcupdate.h>
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+
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+#include <asm/div64.h>
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+
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+struct cpuacct {
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+ struct cgroup_subsys_state css;
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+ spinlock_t lock;
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+ /* total time used by this class */
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+ cputime64_t time;
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+
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+ /* time when next load calculation occurs */
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+ u64 next_interval_check;
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+
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+ /* time used in current period */
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+ cputime64_t current_interval_time;
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+
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+ /* time used in last period */
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+ cputime64_t last_interval_time;
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+};
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+
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+struct cgroup_subsys cpuacct_subsys;
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+
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+static inline struct cpuacct *cgroup_ca(struct cgroup *cont)
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+{
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+ return container_of(cgroup_subsys_state(cont, cpuacct_subsys_id),
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+ struct cpuacct, css);
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+}
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+
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+static inline struct cpuacct *task_ca(struct task_struct *task)
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+{
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+ return container_of(task_subsys_state(task, cpuacct_subsys_id),
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+ struct cpuacct, css);
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+}
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+
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+#define INTERVAL (HZ * 10)
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+
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+static inline u64 next_interval_boundary(u64 now)
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+{
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+ /* calculate the next interval boundary beyond the
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+ * current time */
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+ do_div(now, INTERVAL);
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+ return (now + 1) * INTERVAL;
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+}
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+
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+static struct cgroup_subsys_state *cpuacct_create(
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+ struct cgroup_subsys *ss, struct cgroup *cont)
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+{
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+ struct cpuacct *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
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+
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+ if (!ca)
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+ return ERR_PTR(-ENOMEM);
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+ spin_lock_init(&ca->lock);
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+ ca->next_interval_check = next_interval_boundary(get_jiffies_64());
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+ return &ca->css;
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+}
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+
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+static void cpuacct_destroy(struct cgroup_subsys *ss,
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+ struct cgroup *cont)
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+{
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+ kfree(cgroup_ca(cont));
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+}
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+
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+/* Lazily update the load calculation if necessary. Called with ca locked */
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+static void cpuusage_update(struct cpuacct *ca)
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+{
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+ u64 now = get_jiffies_64();
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+
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+ /* If we're not due for an update, return */
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+ if (ca->next_interval_check > now)
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+ return;
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+
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+ if (ca->next_interval_check <= (now - INTERVAL)) {
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+ /* If it's been more than an interval since the last
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+ * check, then catch up - the last interval must have
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+ * been zero load */
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+ ca->last_interval_time = 0;
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+ ca->next_interval_check = next_interval_boundary(now);
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+ } else {
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+ /* If a steal takes the last interval time negative,
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+ * then we just ignore it */
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+ if ((s64)ca->current_interval_time > 0)
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+ ca->last_interval_time = ca->current_interval_time;
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+ else
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+ ca->last_interval_time = 0;
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+ ca->next_interval_check += INTERVAL;
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+ }
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+ ca->current_interval_time = 0;
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+}
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+
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+static u64 cpuusage_read(struct cgroup *cont, struct cftype *cft)
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+{
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+ struct cpuacct *ca = cgroup_ca(cont);
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+ u64 time;
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+
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+ spin_lock_irq(&ca->lock);
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+ cpuusage_update(ca);
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+ time = cputime64_to_jiffies64(ca->time);
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+ spin_unlock_irq(&ca->lock);
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+
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+ /* Convert 64-bit jiffies to seconds */
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+ time *= 1000;
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+ do_div(time, HZ);
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+ return time;
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+}
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+
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+static u64 load_read(struct cgroup *cont, struct cftype *cft)
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+{
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+ struct cpuacct *ca = cgroup_ca(cont);
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+ u64 time;
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+
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+ /* Find the time used in the previous interval */
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+ spin_lock_irq(&ca->lock);
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+ cpuusage_update(ca);
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+ time = cputime64_to_jiffies64(ca->last_interval_time);
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+ spin_unlock_irq(&ca->lock);
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+
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+ /* Convert time to a percentage, to give the load in the
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+ * previous period */
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+ time *= 100;
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+ do_div(time, INTERVAL);
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+
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+ return time;
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+}
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+
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+static struct cftype files[] = {
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+ {
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+ .name = "usage",
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+ .read_uint = cpuusage_read,
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+ },
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+ {
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+ .name = "load",
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+ .read_uint = load_read,
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+ }
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+};
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+
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+static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cont)
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+{
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+ return cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
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+}
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+
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+void cpuacct_charge(struct task_struct *task, cputime_t cputime)
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+{
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+
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+ struct cpuacct *ca;
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+ unsigned long flags;
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+
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+ if (!cpuacct_subsys.active)
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+ return;
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+ rcu_read_lock();
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+ ca = task_ca(task);
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+ if (ca) {
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+ spin_lock_irqsave(&ca->lock, flags);
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+ cpuusage_update(ca);
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+ ca->time = cputime64_add(ca->time, cputime);
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+ ca->current_interval_time =
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+ cputime64_add(ca->current_interval_time, cputime);
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+ spin_unlock_irqrestore(&ca->lock, flags);
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+ }
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+ rcu_read_unlock();
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+}
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+
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+struct cgroup_subsys cpuacct_subsys = {
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+ .name = "cpuacct",
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+ .create = cpuacct_create,
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+ .destroy = cpuacct_destroy,
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+ .populate = cpuacct_populate,
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+ .subsys_id = cpuacct_subsys_id,
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+};
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Paul Menage